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Welcoming iPod touch's control enhancements

Posted: 17 Oct 2008 ?? ?Print Version ?Bookmark and Share

Keywords:iPod? iPhone 3G? multimedia player? teardown?

On Sept. 9, Apple announced a new line of iPods. This lineup included changes to the shuffle, nano and touch. Semiconductor Insights (SI) was eager to identify what components were different between the first- and second-generation touches, as well as compare them with the iPhone 3G, which was released only months ago.

The iPod touch provides technology improvements that put it at par with iPhone when employed as a multimedia player. The screen size and resolution are the same, but speakers were added, as opposed to the piezoelectric sound from the past generation, which was only used to make the basic sounds, like clicking when the device was unlocked. The volume can be controlled using an external button instead of changing the levels on the touchscreen. This has been a feature of the iPhone, and is a good addition to the touch. Its battery life has been extended to about an hour during video playback and eight hours during music playback.

Set of innovations
We identified two significant component changes in the iPod touch. First, the 8Gbyte iPod touch contains Micron NAND Flash. The earlier touch had memory supplied by Samsung and the iPhone 3G uses Toshiba. This shows that Apple is no longer playing favorites with any memory manufacturer. In the past, Apple had an agreement with Samsung to provide the memory devices, but that has apparently expired. Samsung memory has not been involved in the iPhone 3G or second-generation iPod touch systems we analyzed. The reason perhaps is that other makers are offering an affordable price that Apple demand is too high for any single vendor to handle or that the company has multiple second-source vendors to ensure a sufficient supply of NAND flash.

The second change was the inclusion of the Broadcom BCM4325. This is a low-power 802.11 a/b/g with Bluetooth 2.1 + enhanced data rate (EDR) and an FM receiver. This device provides the wireless connectivity to access Websites, iTunes and application store and communicate with accessories like the Nike+ iPod sensor, which does not need the sports kit when used with the second-generation iPod touch. The Wi-Fi feature has two options, either a single-band 2.4GHz 802.11 b/g or a dual-band 2.4GHz and 5GHz 802.11 a/b/g. The part number referenced on the device taken from the second-generation Apple iPod Touch is BCM4325GKWBG, which is the single-band solution.

This shows the die photo of Broadcom BCM4325 Bluetooth and FM receiver.

Unpredictable moves
When the iPhone 3G was launched, there was rumor that Apple would be choosing an IC for the Wi-Fi and Bluetooth capabilities. It was surprising, then, that Apple used a two-chip solution such as the Wi-Fi powered by Marvell's 88W8686 and the Bluetooth from Cambridge Silicon Radio's BlueCore6 device.

The Broadcom device was manufactured using a 65nm process technology. This uses a die size of 6.5mm x 5.8mm = 37.7 mm? in a Wafer-Level Chip-Scale Package (WLCSP). Compared with the two components from Marvell, measuring 4.7mm x 4.1mm = 19.3 mm?, and CSR plc, which has 3.5mm x 3.2mm = 11.2 mm?, this is an increase of about 7 mm?, but it does not consider that more board real-estate is taken up with traces to connect the two devices.

The advanced design techniques help the BCM4325 to deliver the functionality in a power-efficient manner to extend the battery life in consumer products. An integrated power-management unit eases the power topology of the system. The flexible power amplifier scheme, allowing both internal and external power amplifiers, enables the solution to fit multiple mobile applications.

The BCM4325 is designed to address the needs of mobile devices that require less power consumption and better operation. Broadcom's integrated solution gives advanced coexistence algorithms to maximize the performance of multiple wireless connectivity options within a single device. Even as FM radio continues to gain momentum in mobile systems, Broadcom's implementation provides the advanced features needed for entertainment and live news broadcast reception in today's handsets.

This shows the die marking of Broadcom's BCM4325 Bluetooth and wireless receiver.

Getting better
Apple has not indicated that the iPod touch even had Bluetooth functionality. Although the Broadcom device has the capability, there are no any applications yet to take advantage of this feature.

So has Apple tipped its hand about new features for the iPod touch? There are many applications that could easily be added to the player with only a slight change to the firmware code. With the ability to connect wirelessly to the Internet, Apple could introduce VoIP capabilities with a Bluetooth headset, or even just add Bluetooth wireless stereo headphones for listening to music.

It could just be a cost-cutting measureApple may have been able to get a volume-purchase price that made it a cost-effective solution for the iPhone and the iPod touch, even if all the functionality might not be enabled in the latter. Further analysis of an iPhone 3G is needed to determine if Broadcom is being designed into that system as well.

- Gregory Quirk
EE Times

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